scope:

This standard describes sounding of the atmosphere using ground-based weather radar systems at wavelengths between 3 cm and 10 cm. These systems are suitable for area-wide detection of precipitation and other targets up to an altitude of several 1000 m above ground. In addition, Annex A describes vertical soundings using a micro rain radar.

The main application described here is quantitative precipitation measurement. Area-wide detection of precipitation areas opens a series of important applications. One popular qualitative application is the real-time display of precipitation areas, and the distribution of these displays e.g. on various Internet portals accessible to the general public. Many professional users utilise the data obtained by the radar network sometimes by supplementary special radar stations, to detect the precipitation distribution. For such users the quantitative precipitation estimation is of great importance. For this reason, Part 20 covers not only measurement techniques per se but also the procedures used in the preparation of the data for various applications, for example

• meteorology

• aviation and shipping

• passenger and goods transport

• disaster prevention

• agriculture

• water management (including urban water management and bathing waters)

• support for performing measurement campaigns

• insurrance and general business

• sports events

• catering

• construction site alerts

Using the example of water management, Section 13 describes in detail the following practice-relevant applications and their requirements:

• real-time control (RTC) of sewers

• management of sewage treatment plants

• flood warning services

• management of reservoirs

• flood management

• precipitation climatology

• proof and design of structures

• calibration of hydrological models

• event documentation and analysis

Beyond these, the weather radar offers further applications:

• short-term precipitation forecasting (nowcasting, see Section 12)

• weather modelling and forecasting: Radar data are used inter alia to verify meteorological models, to improve meteorological forecasting through the assimilation of radar data into weather models and to verify other precipitation measurement methods (e.g. by satellite).

• meteorological process studies: Radar data are also utilised for further meteorological research, e.g. to investigate the evolution of convective cells, large scale long-term data for analysing the regional extend and spatial distribution of precipitation (precipitation climatology), large scale (also qualitative) data for synoptic analyses.

• air quality (BImSchG), atmospheric dispersion modeling: Wet deposition in the atmospheric dispersion modeling is frequently parameterized based on the precipitation intensity. The Lagrangian particle model of standard VDI 3945 Part 3 allows - detected by weather radar - to evaluate spatially fine structured precipitation patterns to calculate fine structured fields of wet deposition.

This standard does not discuss these last three points.

This standard does not describe radars on moving platforms (aircraft, ships), which currently are of importance only in research and in marine safety; nor does it deal with weather forecasting methods used in combination with numerical weather models.

Due to their low reflectivity factors, clouds and fog are seen with a standard weather radar only in very rare cases. Observation of clouds relies preferentially on radar systems with wavelengths in the millimetre range. These systems are also not described here.